Urinary tract infection (UTI) is the most common indication for prescribing antibiotics in nursing home residents. To date, criteria for surveillance, diagnosis, and treatment of UTI in nursing home residents have been derived by consensus rather than empirical data. Lack of criteria from empirical evidence leaves nursing home practitioners with the common clinical dilemma of deciding whether nonspecific clinical changes (e.g., fever, altered mental status) are attributable to UTI and whether treatment will benefit clinical outcome. A key step to identifying who should receive antibiotics is to empirically determine diagnostic criteria, including both clinical and laboratory features. The long-term OBJECTIVE of this line of investigation is to identify the subset of nursing home residents with laboratory evidence of UTI (i.e., bacteriuria plus pyuria) in which antibiotic therapy reduces adverse outcomes (i.e., bacteremia, functional decline, death). The SPECIFIC AIM of this proposed research is to identify clinical features that are associated with laboratory evidence of UTI (bacteriuria [>100,000 colony forming units on urine culture] plus pyuria [>10 white blood cells on urinalysis]). Our a priori HYPOTHESIS is that specific clinical features (i.e., change in mental status, fever, change in voiding pattern) will be associated with laboratory evidence of UTI. This observational cohort study will be conducted at five New Haven area nursing homes with a sample size estimate of 493 residents. Persons aged 65 years or older will undergo baseline assessment upon enrollment and repeat assessment when suspected of having UTI. A logistic regression model will be used to determine bivariate and multivariable associations between clinical features and laboratory evidence of UTI. A ROC curve will be calculated from the final multivariable logistic regression model. Those clinical features independently associated with laboratory evidence of UTI will be combined with bacteriuria and pyuria to create an evidence-based definition of UTI. Identifying clinically relevant UTI in nursing home residents is a common dilemma with important functional, economic, and infection control implications. This study will create an evidence-based definition of UTI. Future studies will identify residents with UTI in whom antibiotic therapy improves clinical outcome. [unreadable] [unreadable] [unreadable]